The main goal of prewriting is to generate ideas. The main goal of drafting is two-fold: to create a purpose for writing and to get words on paper. Why not just dive in? Plan first and you’ll find revising (the next step of the writing process) will be a whole lot easier.
To discover your writing purpose, consider:
1. Who are my readers?
2. What do I want them to know?
3. Why do I want them to know this
These three questions will get at the heart of three essentials to writing: Audience, Focus, and Thesis, which together form your purpose for writing.
Audience: who you are writing for. Who you are addressing will determine what you say and how you say it.
Focus: what you want your readers to know. You should have figured out in prewriting. If you’re still struggling with it, it’s best to do a few more prewriting exercises before trying to move on.
Thesis: why you want readers to know this. Together with your focus, knowing your thesis will help you determine your purpose for writing. All good writing has a clear purpose.
Once you’ve created a purpose for writing, keep it in mind as you begin drafting.
This being said, don’t over-scrutinize your work as you write. Your main goal in creating a first draft is just to get words on paper. There will be plenty of time to make it good in the next stage of the writing process: revising.
Note: you may think that creating a writing purpose applies only to non-fiction. Not true! I’m not a literary agent, but I’d bet much of the fiction they reject stems from the writer not considering who, what, or why as they created their story.